Generally, a display device means a device for displaying a video signal input from an external device. Examples of such a display device include a monitor for displaying an image sent from a computer and a television for displaying video and audio signals transmitted from a broadcasting station and also all types of devices displaying an image input from an external device.
High definition large screen display devices are in the spotlight recently in which a flat panel display module (e.g., a liquid crystal display (LCD) and a plasma display panel (PDP)) is mounted.
Meanwhile, various contents including 3D movies, 3D sports broadcasting programs and 3D games associated with 3D technology are increasing, as 3D graphic contents are produced and display technology is developing. Accordingly, supply of display devices displaying 3D images is increasing more and more.
A stereoscopic image for representing a three dimensional image is reliant on a stereo vision of two eyes. Binocular disparity which is a distance between two eyes separated 65 mm apart is the most important factor.
Specifically, right and left human eyes are watching 2D images related to each other, respectively, and the two images are sent to the brain through the retina. The brain converges the images and represents the depth and reality of the 3D image. Such a human capacity is called “stereography”.
A method for viewing a 3D image in a state of wearing specific eyeglasses (in other words, 3D eyeglasses or stereoscopic eyeglasses) is typically offered. The 3D eyeglasses may be classified into polarized eyeglasses, time-sharing eyeglasses and concentration difference eyeglasses. The polarized eyeglasses use a direction of polarized light vibration or rotation and the time-sharing eyeglasses alternatively offer right and left images and the concentration difference eyeglasses transmit lights having a different concentration to right and left eyes, respectively.
A user wearing eyeglasses for vision correction can additionally wear 3D eyeglasses to make the 3D eyeglasses overlapped with the eyeglasses for vision correction. Accordingly, the user usually wearing the eyeglasses for vision correction has to carry the 3D eyeglasses to view 3D graphic contents.
In addition, such the 3D eyeglasses have to be stored and displayed for spectators in a theater where a 3D movie is played.
However, the 3D eyeglasses are fixedly spread to be put on the user immediately such that it is inconvenient to keep or transport the 3D eyeglasses and that the 3D eyeglasses take much space.
Moreover, a fixed gap is between two lenses of the 3D eyeglasses such that it may be difficult for the user to adjust the gap between the lenses.